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How it Works: Eliminating the Edge Effect

When culturing cells for use in, for example, drug screening assays, maintaining consistently high throughput is essential.

by Thermo Fisher Scientific
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Problem: When culturing cells for use in, for example, drug screening assays, maintaining consistently high throughput is essential. However, in order to achieve this while obtaining reliable data, evaporation and consequent well-to-well variability must be significantly minimized. This is commonly experienced as the result of the ‘edge effect’, where medium from the wells during incubation is evaporated. As a phenomena which is especially prominent in the wells close to the perimeter of the plate (the edge wells), this can be highly problematic. As the medium evaporates, concentrations are altered and differential rates of evaporation across the plate results in variability. When a volume loss as small as 10% can concentrate media components and metabolites enough to alter cell physiology, this can have a detrimental effect.

In an attempt to alleviate the edge effect, researchers often decide not to culture cells in the outermost wells but to fill these with sterile water, and use only the inner wells of each plate for cell cultures. However, by rendering these wells unusable, throughput and efficiency become compromised instead.

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Solution: In order to increase the throughput and efficiency of cell culture protocols, researchers need to be able to use all of the wells of a plate with confidence. As such, the Thermo Scientific Nunc Edge Plate has been designed with an evaporation buffer zone built into its perimeter. This can be filled with sterile water or 0.5% agarose, providing an additional reservoir that effectively eliminates the edge effect.

The Nunc™ Edge plate reduces the overall plate evaporation rate to <2% following seven days of incubation, making it ideal for high-throughput cellular assays requiring repeatable results. Thus, more viable and healthy cells are obtained for use in downstream applications. By significantly reducing the occurrence of any media evaporation, sample concentrations are maintained over long periods of incubation. The prevention of cell death and toxicity in the plates’ outer wells allows results to remain more true to the population phenotype, for more efficient high-throughput analysis.

By filling the evaporation buffer zone with 5% agarose, a more solid, jellylike moat is provided, eliminating the potential for any spillages. This provides the same low plate evaporation as water, maintaining evaporation rates at <2% after seven days of incubation, in comparison with over 8% observed with a standard plate. As a result, the plates can be used as standalone, or combined into a fully automated workflow, without the risk of liquid spillages by robotic arms.

By combining advanced optical properties with a low evaporation rate, the Thermo Scientific Nunc Edge Plates enable researchers to obtain quality data from automated fluorescence imaging and quantitative analysis protocols. The dramatic reduction in evaporation enables concentrations to remain consistent across all wells and thus, efficient cell growth is obtained across the entire plate.

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